blackberry bushes

Question

2 questions:

1. I have two bushes that are prolific with flowers and then red berries. But, the berries never get large and are bitter when they turn black.

2. These large non-fruit producing stems keep popping up. I keep cutting them back. Is this the right thing to do and why do they grow?

Answer 1

It sounds like your plants are getting witches broom. The disease causes those stems and also saps energy away from producing stems, which means inferior, poor tasting fruit. This article will have more information and how to control it:
http://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-FR-S-3.pdf